. >> about 23% of all u.s. motorocyclists are women. >> reporter: karen davidson says anyone can learn to ride. >> you've got your clutch pulled in. we're going to have you start the engine. >> reporter: all right. >> you're not going to go anywhere. put your hand over there. when you put your thumb on there and press and hold it for a second (engine starts) >> reporter: (laughing nervously) but there are want a be motorcycle riders and the real thing. women like 26-year-old melissa paris. she races against male riders going 168 miles an hour on the daytona speedway. >> i'm told, "you're the fastest woman around." >> reporter: is that true? >> not my ultimate goal to be the fastest girl. i'm trying to focus on being as fast as everyone else. it's the only sport where we're on a level playing field with men. >> reporter: she may be the only rider on the track whose fingernails match her bike, but she concedes nothing to the competition. including her husband, motorcycle racing champion josh hayes. who is is fast